Type action drive

ABSTRACT

A type action has a driven lever carrying a rotary cam cooperating with the power roll. When a key lever is operated, it displaces a control lever so that the same is shifted from a rest position resiliently arrested by a tension spring, to an operative position in which the spring moves the control lever to turn the cam to a driven position engaged and rotated by the power roll so that the driven lever is operated. The turning cam also moves the control lever back toward the rest position so that the spring is again tensioned. When the cam separates from the power roll to permit inertia movement of the driven lever to obtain an impact by the type bar, the control lever, operated by the tension spring, turns the cam back to its initial position. Ball locking means cooperate with the control levers so that only one control lever at a time can be moved to the operative position while a control lever, later actuated by a key lever, abuts the locking balls and moves to the operative position when the first actuated control lever releases the locking means.

United States Patent 91 Rix et a1.

[ 1*Dec. 11, 1973 TYPE ACTION DRIVE [73] Assignee: Olympia Werke AG,

Wilhelmshaven, Germany Notice: The portion of the term of this patent subsequent to Feb. 6, 1990, has been disclaimed.

[22] Filed: July 22, 1970 [21] Appl. No.: 62,781

30 Foreign Application Priority Data 1,932,914 10/1933 Shelton et al 197/16 X 1,963,285 6/1934 Woodward 197/17 X 3,152,759 10/1964 May 197/98 UX 3,181,680 5/1965 Cappotto et al. 197/17 3,191,740 6/1965 Smusz et a1 197/16 3,353,646 11/1967 Young 197/16 Primary Examiner-Ernest T. Wright, Jr. Attorney-Michael S. Striker [57] ABSTRACT A type action has a driven lever carrying a rotary cam cooperating with the power roll. When a key lever is operated, it displaces a control lever so that the same is shifted from a rest position resiliently arrested by a tension spring, to an operative position in which the spring moves the control lever to turn the cam to a driven position engaged and rotated by the power roll so that the driven lever is operated. The turning cam also moves the control lever back toward the rest position so that the spring is again tensioned. When the cam separates from the power roll to permit inertia movement of the driven lever to obtain an impact by the type bar, the control lever, operated by the tension spring, turns the cam back to its initial position. Ball locking means cooperate with the control levers so that only one control lever at a time can be moved to the operative position while a control lever, later actuated by a key lever, abuts the locking balls and moves to the operative position when the first actuated control lever releases the locking means.

10 Claims, 4 Drawing Figures TYPE ACTION DRIVE BACKGROUND OF THE INVENTION The present invention relates to a type action drive for data processing machines, particularly for electric typewriters whose type actions include driven levers carrying rotary cams cooperating with a power roll. In type action drives of electric typewriters it is of particular importance that all moving parts of the drive, rapidly return to the initial position, in order to be ready for the next operation so that a-high typing speed is obtained.

It has been proposed to provide a control .carn with a resilient means by which it is returned to its initial position after causing actuation of a type action. However, this device requires a great number of cooperating components, whichare expensive to manufacture. Another disadvantage of this device resides in that the separation of the cam from the power roll is obtained by lifting the cam from the power roll. The driving connection is terminated sooner or later, in order to adjust the transferred energy, as is required for the adjustment of the impact force of the type bars. Such a separation causes wear of the engaging parts, and reduces the span of useful life of the device SUMMARY OF THE INVENTION It is one object of the invention to provide a type action drive of simple construction and consisting of few components so as to be suited for mass production.

Another object of the invention is to provide a type action drive which operates at highspeed with great precision, and reliably operates for a long span of life.

Another object of the invention is to provide a typewriter with type action drives which permit the operation of the typewriter at very high typing speeds.

With these objects in view, the present invention provides control means with cam follower means which cooperate with cam portions of a rotary cam mounted on a driven lever which is partof a type action. The control means are operable by an actuating pulse, for example by key operation, out of a rest position whereupon tensioned spring means move the control means to turn the cam to a position engaged by .the power means. When the cam is driven by the power means, the control means are turned back by the cam and the spring means is again tensioned. Due to the alternating operation of the cam by the control means, and of the control means by the cams, a precise function of the .type action drive is assured.

In constructions according to the prior art, the peripheral speed of the cam at the moment in which it engages the continuously rotating power roll, is very small so that upon engagement of the cam by the power roll, slipping takes place which causes great wear.

This is avoided in the present invention since the cam has impact surfaces for the cam follower portion of the control lever, and the control lever is provided with an opening bounded by a camming edge which has an arresting recess and a mounting recess. A shaft passes through the opening, and due to the action of the spring, the arresting recess engages the shaft in the rest position of the control lever, while the mounting recess engages the shaft in the operative position of the control lever in which the same is turnable about the shaft.

In accordance with the invention, the cam is moved into engagement with the power roll by the energy stored in the tensioned spring, and the respective track portion of the cam moves tangentially to the cylindrical surface of the power roll, and at substantially the same speed, so that no slipping takes place which may cause wear.

In order to obtain high peripheral speeds of the cam, certain kinematic conditions are provided. On the one hand, the turning moment exerted by the tension spring by means of the control lever on the cam is selected to be as great as possible, and to be constant during the drive of the cam by the power roll. This can be obtained by a suitable form of the cam track. On the other hand, the parts are preferably made of lightweight material in order to reduce the inertia of the moving parts.

The novel features which are considered as characteristic for the invention are set, forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary perspective view illustrating an embodiment of the invention;

FIG. 2 is a fragmentary side elevation of the embodiment of FIG. 1, showing a first type action in a normal position of rest, and a second type action displaced by operation of a key;

FIG. 3 is a fragmentary side elevation illustrating the beginning of the cooperation with the power roll; and

FIG. 4 is a fragmentary side elevation illustrating the type action near the end of the drive by the power roll.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, FIG. 1 illustrates only one type action of a row of type actions. A type bar 9 with a type is mounted for angular movement on a curved shaft 9a in a type segment 9b, and is connected by a wire 7 to one end of a driven means or lever 3 which is mounted on supporting means including a shaft 5 on the supporting frame 10 of the typewriter and is biased by a spring 1 secured to supporting frame 10. A cam 25 is rotatably mounted on one arm of driven lever 3, and includes a drive cam portion having a cam track portion 22, and a control cam portion 25a having two projecting track portions 225 and 325, between which a recessed track portion 225a is provided. The track portion 22 of drive cam portion 125 cooperates with a power roll 27 which is mounted in the machine frame and continuously rotates in clockwise direction, as indicated by an arrow. A shaft 1 I, mounted on the machine frame, supports key levers 13 for angular movement in the slots 14a of a fixed structure 14. Each key lever 13 is tensioned by a spring 17 to assume a normal position of rest in which the respective key 15 can be depressed for starting an operation of the respective type action 25, 3, 7, 9.

Another shaft 21 is mounted on a frame part 10a, and serves as a mounting means for control means or levers 19, of which only one is shown in FIG. 1. Each control lever 19 has a cam follower portion 619 which, in the rest position of the type action, is-located in recess 225a engaging the cam track portion 225 with a nose 425, as best shown for the higher control lever 19 in FIG. 2. The other end of each control lever 19 has an abutment 819 cooperating with an abutment stop 33 provided on frame 10. Lever 19 has a mounting portion having an opening 19a through which shaft 21 passes. Each opening 19a is surrounded by a collar shaped camming edge 119 having an inner camming surface formed with an arresting recess 219, and with a mounting recess 319. I

A comb-shaped resilient spring means 23 whose prongs 123 are leaf springs is mounted on the machine frame, and each of the leaf spring prongs 123 abuts a transverse projection 419 of the respective control lever 19. In the rest position shown for the upper control lever 19 in FIG. 2, the respective leaf spring prong 123 abuts a bulge 519 of the transverse projection 419, and exerts pressure on the control lever 19 acting in such a direction as to urge the arresting recess 219 of the camming edge 119 into engagement with the fixed arresting shaft 21 so that control lever 19 is resiliently arrested in a rest position. When a key lever 13 is depressed by operation of the respective key 15, the projection 113 engages the upper edge 919 of the respective control lever 19 and displaces the same so that arresting recess 219 is shifted relative to the arresting shaft 21 which enters the mounting recess 319 as shown for the lower control lever 19 in FIG. 2 so that the control lever 19 is in an operative position in which it can turn due to the pressure of a spring prong 123. Key means 13, 15 has to be manually displaced only a small distance to overcome the resilient force of the leaf spring prong 123 for release of arresting shaft 21 by the arresting recess 219. Thereupon, control lever 19 is displaced by the respective leaf spring prong 123 to move to an operative position in which shaft 21 is located in the mounting recess 319, first assuming the operative position in which the lower control lever 19 is shown in FIG. 2, and then turned by spring prong 123 to the actuated position of control lever 19 shown in FIG. 3.

During this turning movement of control lever 19, by spring prong 123 cam follower portion 619, which in the initial position of rest shown for the upper control lever 19 in FIG. 2, is located in a recessed cam track portion 225a, turns cam 25 in counterclockwise direction on driven lever 3 out of the inactive position so that the cam track portion 22 is first moved toward the surface of the power roll 27, as shown in FIG. 2, and then engages the same in a driven position, as shown in FIG. 3. This turning movement of cam 25 is effected by control lever 19 due to the resilient action of the respective spring prong 123, and is independent of the key lever movement so that the operator can release the respective key 15 for return to the normal position by spring 17, shown in FIG. 1. Each control lever 19 has a locking portion 719 which enters during this movement between two balls 29a of a conventional locking device 29 so that, when another key 15 is operated, the respective other control lever 19 cannot actuate the respective other cam 25 since the ball locking device 29 does not permit another locking portion 719 to enter between two other balls 29a. However, the other locking portion 719 abuts two adjacent balls 29a due to the pressure of the respective spring prong 123. Since the arresting recess 219 of the respective other control lever 19 has already released arresting shaft 21, the pressure of the respective other leaf spring prong 123 urges the respective other control lever 19 to the position shown in FIG. 3 as soon as the locking portion 719 of the first actuated control lever 19 moves out of the locking device 29, as will be explained hereinafter in greater detail. In this manner a very rapid succession of operations of different type actions is possible, since the information as to which type action 25,3, 7, 9 is to be next operated, is stored by operation of the next following key means 13, I5 and remains stored after the same has been returned to its normal position. Preferably, springs, not shown, are provided at opposite ends of the row of locking balls 29a so that always the same force is required for pressing a locking portion 719 of a control lever 19 into the space between two locking balls 29a.

As shown in FIG. 3, the point of cam track portion 22 which first engages the surface of power roll 27, moves at the moment of engagement in a direction which is tangential to the movement of the outer cylindrical periphery of power roll 27, so that no relative slippage takes place. Also, the force of spring prong 123 is selected to that control lever 19 accelerates rotary cam 25 to such a degree that the track portion 22 moves at the same speed as the peripheral surface of power roll 27, so that no relative slippage and consequent wear takes place.

When the leading point of track portion 22 engages the power roll 27 in the position of FIG. 3, cam 25 is rotated in counterclockwise direction to theposition shown in FIG. 4. Due to the eccentric shape of cam track 22, driven lever 3 turns in clockwise direction about shaft 5 so that type bar 9 is actuated and starts its movement.

At the same time, the rising track portion of cam portion 25a acts on nose 425 of cam follower portion 619 of control lever 19 to turn the same toward the initial rest position while the abutment portion 819 of control lever 19 abuts the stop 33 as shown in FIG. 4.

This angular movement of control lever 19 places arresting shaft 21 outside of mounting recess 319, and at the same time, the bulge 519 of the transverse projection 419 of control lever 19, tensions the respective leaf spring prong 123 by a force transmitted from power roll 27 through cam 25 and cam portion 25a to control lever 19.

When the track portion 22 of the drive cam portion 125 runs off the outer surface of the power roll 27, the same is separated from cam means 25 since driven lever 3 continues its angular movement in clockwise direction due to the force of inertia until the type bar 9 produces an impact on the writing surface whose force is determined by the kinetic energy stored in the freely moving type action 25, 3, 7, 9.

Since cam 25 is separated from the power roll 27 by this movement of driven lever 3, the force of leaf spring 123, acting through control lever 19 and cam follower portion 619 on cam track 225 of cam 25, turns cam portion 25a in counterclockwise direction back to the initial inactive position of rest which is possible due to the separation of cam 25 from the power roll 27. Spring prong 123 then urges Control lever 19 to a position in which arresting shaft 21 is located in the arresting recess 219, so that control lever 19 is again in its position of rest, and the next following type action operation can take place. While control lever 19 is moved by spring prong 123 in counterclockwise direction to move cam 25 back to its initial inactive position, abutment portion 819 moves away from stop 33 so that the locking portion 719 is released by the ball locking device 29, permitting the locking portion 719 of another control lever 19 to enter between two balls 29a of the ball locking device 29. As explained above, the respective other control lever 19 may already be in a position in which its locking portion 719 abuts two balls 29a under the action of the respective. other spring prong 123, completely separated from projection 113 of key lever 13.

In the event that two control levers 19 are actuated exactly at the same time by simultaneous operation of two keys 15, the ball locking device 29 permits none of the locking portions 719 to enter between the balls 29a, so that the two control levers 19 cannot effect operations of the respective type actions. A special lever 30, see FIG. 3, is then operated to turn the releasing bar 31 to a position in which its flat face 31a engages the two control levers 19, and pushes the same to the rest position in which arresting shaft 21 is located in the arrest ing recesses 219 of both actuated control levers 19. Releasing bar 31 has pins 36 at the ends, mounted in bearings, not shown, in frame 10. A spring 32 urges lever 30 to a position of rest abutting a fixed stop 34.

As explained above, cam 25 performs an angular movement first in counterclockwise, and then in clockwise direction during each type action operation. In the event that a type action 25, 3, 7, 9 is blocked while power roll 27 engages the track portion 22 of cam 25 and drives the type action 25, 3, 7, 9, cam 25 performs a complete revolution, so that no wear occurs on the power roll 27 and on cam 25.

The shape of track portion 22 is selected so that the engagement of the leading end of the same with the power roll 27, and also the separation of the trailing end of the same from the power roll 27, takes place in tangential direction with respect to the surface of the power roll 27. Consequently, the separation takes place when the trailing end of track portion 22 is in contact with the power roll 27, and not sooner or later. Therefore, driven lever 3 moves always at the same speed when cam 25 separates from power roll 27, so that always the same amount of kinetic energy is stored in the type action, and each type 9c acts with the same impact force. Means, shown in FIGS. 3 and 4, are provided for regulating and adjusting the impact force of individual type bars 9 in accordance with the area of a character on the type face of a type 90 so that the impact force of a large letter is greater than the impact force of a small symbol. An adjusting screw 28 is threaded into a bore of a wall 26 of frame 10, and secured to a spring 24 anchored in a hole 3a in driven lever 3. By adjustment of screw 28, the resilient force which counteracts the movement of the type bar 9 to the printing position, is varied according to the respective type 90.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of type action drives differing from the types described above.

While the invention has been illustrated and described as embodied in a type action drive in which an eccentric cam cooperating with the power roll is controlled by control means biassed by spring means, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. Type action drive comprising driven means; means supporting said driven means for type actuating movement; power roll means; cam means mounted on said driven means for movement with said driven means and also for relative turning movement between an inactive position, and a driven position engaging and driven by said power roll means; control means continuously engaging said cam means; mounting means for mounting said control means movably between a rest position engaging said cam means and an operative position, and

also for turning movement in said operative position to an actuated position, said mounting means including arresting means; spring means engaging said control means and being tensioned in said'rest position for resiliently holding said control means in engagement with said arresting means so that said control means is arrested in said rest position against movement by said spring means to said operative position, said spring means urging said control means from said operative position to said actuated position; key means movable to a depressed position displacing said control means against the action of said spring means out of said rest position to said operative position in which said control means is turned by said spring means to said actuated position so that said control means turn said cam means from said inactive position to said driven position whereby said power roll means rotates said cam means for driving said driven means, and for moving said control means back toward said rest position while tensioning said spring means until said cam means separates from said power roll means, and said driven means continues to move by inertia so that said tensioned spring means bias said control means to turn said cam means relative to said driven means to said inactive position, and then urge said control means to said rest position engaging said arresting means.

2. A type action drive as claimed in claim 1 wherein said power roll means includes a continuously rotatable power roll; and wherein said cam means includes a first cam portion having a first cam track cooperating with said power roll in said driven position of said cam means, and a second cam portion having a second cam track; and wherein said control means has a cam follower portion engaging said second cam track in said inactive and driven positions of said cam means.

3. A type action drive as claimed in claim 1 wherein said control means include a cam follower portion biassed by said spring means into engagement with said cam means in both said inactive and driven position of said cam means; and wherein said cam means has a cam track including a recessed track portion engaged by said cam follower portion in said rest position, and a rising track portion engaged by said cam follower portion during rotation of said cam means.

4. A type action drive as claimed in claim 1 wherein said control means includes a cam follower portion engaging said cam means, and a mounting portion forming a camming edge surrounding an opening, said camming edge having an arresting recess and a mounting recess; wherein said arresting means include a stationary shaft passing through said opening; and wherein said spring means bias said control means to engage said shaft in said arresting recess in said rest position of said control means, and to engage said shaft in said mounting recess in said operative position; wherein said shaft when in said mounting recess supports said control means for turning movement, and resiliently arrests said control means when located in said arresting recess; and wherein said arresting recess, control means, and said spring means resiliently yield, and said camming edge moves along said shaft to engage said mounting recess when said key means moves said control means from said rest position to said operative position.

5. A plurality of type action drives as claimed in claim 1 wherein said control means of each type action drive includes a locking portion; and comprising a ball locking device with a confined row of balls and positioned so that said locking portion of any one control means in said operative position enters between two balls so that the locking portion of another control means displaced by an other key means can not enter between an other two balls but abuts said other two balls until said one control means moving toward said rest position retracts the locking portion thereof from said balls whereupon said spring means displace said other control means to enter between said other two balls with the locking portion thereof independently of the respective key means.

6. A type action drive as claimed in claim 1 wherein said spring means include a comb-shaped means having leaf spring prongs; and wherein one of said leaf spring prongs resiliently abuts said control means.

7. A type action drive as claimed in claim 1 wherein said power roll means includes a continuously rotatable power roll; and wherein said cam means includes a first cam portion having a first cam track cooperating with said power roll in said driven position of said cam means, and a second cam portion having a second cam track; wherein said control means has a cam follower portion engaging said second cam track in said inactive and driven positions of said cam means; wherein said second cam track includes a recessed cam track portion engaged by said cam follower portion in said rest position, and a rising cam track portion engaged by said cam follower portion during rotation of said cam means; wherein said control means has a mounting portion forming a camming edge surrounding an opening, said camming edge having an arresting recess and a mounting recess; wherein said arresting means include a stationary shaft passing through said opening; and wherein said spring means bias said control means to engage said shaft in said arresting recess in said rest position of said control means, and to engage said shaft in said mounting recess in said operative position; wherein said shaft when in said mounting recess supports said control means for turning movement, and resiliently arrests said control means when located in said arresting recess; and wherein said arresting recess, said control means, and said spring means resiliently yield, and said camming edge moves along said shaft to engage said mounting recess when said key means moves said control means from said rest position to said operative position.

8. A type action drive as claimed in claim 1 wherein said power roll means includes a rotary driven power roll having a cylindrical surface movable at a predetermined peripheral speed; wherein said cam means has a cam track portion cooperating with said cylindrical surface of said power roll; and wherein said cam means is turned by said spring means from said inactive position to said driven position so that said cam track portion moves tangentially to said cylindrical surface and at a speed which is substantially equal to said peripheral speed when said cam track portion engages said cylindrical surface whereby wear of said cylindrical surface and of said cam track portion is low.

9. Type action drive comprising driven means; means supporting said driven means for type actuating movement; power roll means; cam means mounted on said driven means for movement with said driven means, and also for turning movement relative to said driven means between an inactive position, and a driven position driven by said power roll means; control means including a control lever having a cam follower portion at one end, an abutment portion at the other end, and a mounting portion between said ends, said mounting portion forming a camming edge surrounding an opening, said camming edge having an arresting recess and a mounting recess; mounting means including a stationary shaft passing through said opening, said mounting means mounting said controlv means movably between a rest position in which said arresting recess engages said shaft, and an operative position in which said mounting recess engages said shaft for supporting said control means for turning movement; key means operable for moving said control means from said rest position to said operative position; spring means engaging said control means and balancing said control means to engage said shaft in said arresting recess in said rest position of said control means, and to engage said shaft in said mounting recess in said operative position, said spring means being tensioned in said rest position for resiliently holding said control means in said rest position, and for turning said control means when said control means is in said operative position so that said control means turns said cam means from said inactive position to said driven position whereby said power roll means rotates said cam means for driving said driven means and for moving said control means back to said rest position while tensioning said spring means until said cam means separates from said power roll means and said driven means continues to move by inertia so that said tensioned spring means biases said control means to turn said cam means relative to said driven means back to said inactive position, said arresting recess, control means and said spring means resiliently yielding, and said camming edge moving along said shaft to engage said mounting recess when said key means moves said control means from said rest position to said operative position; and a stop means engaged by said abutment portion while said control lever is moved back to said rest position by said cam means turning to said inactive position so that said control lever turns about said other end thereof before being urged by said spring means into said rest position in which said arresting recess engages said shaft.

10. Type action drive comprising driven means; means supporting said driven means for type actuating movement; power roll means; cam means mounted on said driven means for movement with said driven means, and also for turning movement relative to said driven means between an inactive position and a driving position driven by said power roll means; control means including a control lever having at one end a cam follower portion engaging said cam means, and having a mounting portion spaced from said one end, said mounting portion forming a camming edge surrounding an opening, said camming edge having an arresting recess and a mounting recess; mounting means for mounting said control means movably between a rest position and an operative position, and also for turning movement in said operative position, said mounting means including a stationary shaft passing through said opening, and engaged by said arresting recess in said position of rest, and by said mounting recess in said operative position; key means operable for moving said control means from said rest position to said operative position and displacing said control lever substantially in the direction of said camming edge between said arresting recess and said mounting recess; spring means engaging said control lever between said cam follower portion and said mounting portion, said camming edge extending transversely to the direction of the force exerted by said spring means on said control lever, said spring means being tensioned in said rest position for resiliently holding said control lever in said rest position, and for turning said control lever when said control lever is in said operative position, said spring means biasing said control means to engage said shaft in said arresting recess in said rest position of said control means, and to engage said shaft in said mounting recess in said operative position, said arresting recess, control means, and said spring means resiliently yielding, and said camming edge moving along said shaft to engage said mounting recess when said key means moves said control lever from said rest position to said operative position, said control lever when turning in said operative position turning said cam means from said inactive position to said driven position whereby said power roll means rotates said cam means for driving said driven means and for moving said control means back toward said rest position while tensioning said spring means until said cam means separates from said power roll means and said driven means continues to move by inertia so that said tension spring means biases said control means to turn said cam means relative to said driven means back to said inactive position, and then bias said control means into said rest position. 

1. Type action drive comprising driven means; means supporting said driven means for type actuating movement; power roll means; cam means mounted on said driven means for movement with said driven means and also for relative turning movement between an inactive position, and a driven position engaging and driven by said power roll means; control means continuously engaging said cam means; mounting means for mounting said control means movably between a rest position engaging said cam means and an operative position, and also for turning movement in said operative position to an actuated position, said mounting means including arresting means; spring means engaging said control means and being tensioned in said rest position for resiliently holding said control means in engagement with said arresting means so that said control means is arrested in said rest position against movement by said spring means to said operative position, said spring means urging said control means from said operative position to said actuated position; key means movable to a depressed position displacing said control means against the action of said spring means out of said rest position to said operative position in which said control means is turned by said spring means to said actuated position so that said control means turn said cam means from said inactive position to said driven position whereby said power roll means rotates said cam means for driving said driven means, and for moving said control means back toward said rest position while tensioning said spring means until said cam means separates from said power roll means, and said driven means continues to move by inertia so that said tensioned spring means bias said control means to turn said cam means relative to said driven means to said inactive position, and then urge said control means to said rest position engaging said arresting means.
 2. A type action drive as claimed in claim 1 wherein said power roll means includes a continuously rotatable power roll; and wherein said cam means includes a first cam portion having a first cam track cooperating with said power roll in said driven position of said cam means, and a second cam portion having a second cam track; and wherein said control means has a cam follower portion engaging said second cam track in said inactive and driven positions of said cam means.
 3. A type action drive as claimed in claim 1 wherein said control means include a cam follower portion biassed by said spring means into engagement with said cam means in both said inactive and driven position of said cam means; and wherein said cam means has a cam track including a recessed track portion engaged by said cam follower portion in said rest position, and a rising track portion engaged by said cam follower portion during rotation of said cam means.
 4. A type action drive as claimed in claim 1 wherein said control means includes a cam follower portion engaging said cam means, and a mounting portion forming a camming edge surrounding an opening, said camming edge having an arresting recess and a mounting recess; wherein said arresting means include a stationary shaft passing through said opening; and wherein said spring means bias said control means to engage said shaft in said arresting recess in said rest position of said control means, and to engage said shaft in said mounting recess in said operative position; wherein said shaft when in said mounting recess supports said control means for turning movement, and resiliently arrests said control means when located in said arresting recess; and wherein said arresting recess, control means, and said spring means resiliently yield, and said camming edge moves along said shaft to engage said mounting recess when said key means moves said control means from said rest position to said operative position.
 5. A plurality of type action drives as claimed in claim 1 wherein said control means of each type action drive includes a locking portIon; and comprising a ball locking device with a confined row of balls and positioned so that said locking portion of any one control means in said operative position enters between two balls so that the locking portion of another control means displaced by an other key means can not enter between an other two balls but abuts said other two balls until said one control means moving toward said rest position retracts the locking portion thereof from said balls whereupon said spring means displace said other control means to enter between said other two balls with the locking portion thereof independently of the respective key means.
 6. A type action drive as claimed in claim 1 wherein said spring means include a comb-shaped means having leaf spring prongs; and wherein one of said leaf spring prongs resiliently abuts said control means.
 7. A type action drive as claimed in claim 1 wherein said power roll means includes a continuously rotatable power roll; and wherein said cam means includes a first cam portion having a first cam track cooperating with said power roll in said driven position of said cam means, and a second cam portion having a second cam track; wherein said control means has a cam follower portion engaging said second cam track in said inactive and driven positions of said cam means; wherein said second cam track includes a recessed cam track portion engaged by said cam follower portion in said rest position, and a rising cam track portion engaged by said cam follower portion during rotation of said cam means; wherein said control means has a mounting portion forming a camming edge surrounding an opening, said camming edge having an arresting recess and a mounting recess; wherein said arresting means include a stationary shaft passing through said opening; and wherein said spring means bias said control means to engage said shaft in said arresting recess in said rest position of said control means, and to engage said shaft in said mounting recess in said operative position; wherein said shaft when in said mounting recess supports said control means for turning movement, and resiliently arrests said control means when located in said arresting recess; and wherein said arresting recess, said control means, and said spring means resiliently yield, and said camming edge moves along said shaft to engage said mounting recess when said key means moves said control means from said rest position to said operative position.
 8. A type action drive as claimed in claim 1 wherein said power roll means includes a rotary driven power roll having a cylindrical surface movable at a predetermined peripheral speed; wherein said cam means has a cam track portion cooperating with said cylindrical surface of said power roll; and wherein said cam means is turned by said spring means from said inactive position to said driven position so that said cam track portion moves tangentially to said cylindrical surface and at a speed which is substantially equal to said peripheral speed when said cam track portion engages said cylindrical surface whereby wear of said cylindrical surface and of said cam track portion is low.
 9. Type action drive comprising driven means; means supporting said driven means for type actuating movement; power roll means; cam means mounted on said driven means for movement with said driven means, and also for turning movement relative to said driven means between an inactive position, and a driven position driven by said power roll means; control means including a control lever having a cam follower portion at one end, an abutment portion at the other end, and a mounting portion between said ends, said mounting portion forming a camming edge surrounding an opening, said camming edge having an arresting recess and a mounting recess; mounting means including a stationary shaft passing through said opening, said mounting means mounting said control means movably between a rest position in which said arresting recess engages said shaft, and an operative posiTion in which said mounting recess engages said shaft for supporting said control means for turning movement; key means operable for moving said control means from said rest position to said operative position; spring means engaging said control means and balancing said control means to engage said shaft in said arresting recess in said rest position of said control means, and to engage said shaft in said mounting recess in said operative position, said spring means being tensioned in said rest position for resiliently holding said control means in said rest position, and for turning said control means when said control means is in said operative position so that said control means turns said cam means from said inactive position to said driven position whereby said power roll means rotates said cam means for driving said driven means and for moving said control means back to said rest position while tensioning said spring means until said cam means separates from said power roll means and said driven means continues to move by inertia so that said tensioned spring means biases said control means to turn said cam means relative to said driven means back to said inactive position, said arresting recess, control means and said spring means resiliently yielding, and said camming edge moving along said shaft to engage said mounting recess when said key means moves said control means from said rest position to said operative position; and a stop means engaged by said abutment portion while said control lever is moved back to said rest position by said cam means turning to said inactive position so that said control lever turns about said other end thereof before being urged by said spring means into said rest position in which said arresting recess engages said shaft.
 10. Type action drive comprising driven means; means supporting said driven means for type actuating movement; power roll means; cam means mounted on said driven means for movement with said driven means, and also for turning movement relative to said driven means between an inactive position and a driving position driven by said power roll means; control means including a control lever having at one end a cam follower portion engaging said cam means, and having a mounting portion spaced from said one end, said mounting portion forming a camming edge surrounding an opening, said camming edge having an arresting recess and a mounting recess; mounting means for mounting said control means movably between a rest position and an operative position, and also for turning movement in said operative position, said mounting means including a stationary shaft passing through said opening, and engaged by said arresting recess in said position of rest, and by said mounting recess in said operative position; key means operable for moving said control means from said rest position to said operative position and displacing said control lever substantially in the direction of said camming edge between said arresting recess and said mounting recess; spring means engaging said control lever between said cam follower portion and said mounting portion, said camming edge extending transversely to the direction of the force exerted by said spring means on said control lever, said spring means being tensioned in said rest position for resiliently holding said control lever in said rest position, and for turning said control lever when said control lever is in said operative position, said spring means biasing said control means to engage said shaft in said arresting recess in said rest position of said control means, and to engage said shaft in said mounting recess in said operative position, said arresting recess, control means, and said spring means resiliently yielding, and said camming edge moving along said shaft to engage said mounting recess when said key means moves said control lever from said rest position to said operative position, said control lever when turning in said operative position turning said cam means from said iNactive position to said driven position whereby said power roll means rotates said cam means for driving said driven means and for moving said control means back toward said rest position while tensioning said spring means until said cam means separates from said power roll means and said driven means continues to move by inertia so that said tension spring means biases said control means to turn said cam means relative to said driven means back to said inactive position, and then bias said control means into said rest position. 